IIHS begins rating cars on ability to avoid rear-impact collisions

The IIHS is looking backward when it comes to vehicle safety. The insurance industry-funded crash-testing group has come up with a new rating system that will help customers identify which cars are most likely to prevent themselves from bumping into things when backing up.

Vehicles are judged on how well they mitigate rearward collisions in car-to-car and car-to-pole tests at several different approach angles and at speeds up to 4 mph. Cars will be ranked in one of three categories—Superior, Advanced, or Basic—based on a points system.

In preliminary testing of six models, the Cadillac XT5 and Subaru Outback received the Superior rating because they were able stop themselves before pricey damage occurred. In a demonstration run, backing into a pole at low speed caused $3,477 in damages to the XT5. The IIHS said that the Cadillac would need repairs for the bumper cover, tailgate, hitch bar, energy absorber, rear body panel, trim, and assorted brackets.

To qualify for a Superior rating, cars must have a rear automatic braking system “that can avoid a crash or substantially reduce speeds in many of the test scenarios.”

According to IIHS , "the more systems covered by the auto braking, the better the rating."

If a car is equipped with rear automatic braking but only manages to avoid contact or reduce speed in some scenarios, then it earns an Aadvanced rating. If rear automatic braking is not offered, rear parking sensors and cross-traffic alerts can garner Basic rating.

The IIHS doesn't factor rearward visibility from the driver's seat into its rating system.